Submersible systems are utilized in a variety of applications, such as subsea applications. For example, pressure and flow controlling devices, such as subsea test trees, facilitate the production of hydrocarbon-based fluids. Other pressure and/or flow control equipment, e.g. horizontal Christmas trees, also are used in subsea applications for the production of desired fluids.
In many subsea applications, there is an increasing demand for smaller trees and wellheads with larger bores and valves to control the flow of wellbore fluids. However, the drift diameters of pressure controlling equipment, such as subsea test trees or horizontal Christmas trees, are limited to certain sizes and/or pressure ratings. This is necessary to accommodate conventional valve closure devices and their corresponding actuator mechanisms which are permanently packaged together.
Additionally, removal of the valve or actuator during servicing or replacement requires disassembly of components of the pressure housing. Generally, such disassembly results in the breaking of “pressure tested” barriers and the loss of pressure integrity within the system. Loss of pressure integrity can result in the outflow of production fluid into the surrounding environment.
With horizontal Christmas trees, for example, if the valve or its actuator fail, it may become necessary to decomplete and seal off the well to maintain pressure integrity while the entire horizontal Christmas tree is recovered for repair. Such an operation is extremely expensive due to both the cost of recovering the Christmas tree as well as the production downtime when the well is sealed.